Reversing a bootloader code (MIPS)

I’m trying to reverse a bootloader code extracted from raw memory dump of data modem. I think I extracted it correctly.
Bootloader size 32768 bytes. Device use BCM3382 CPU (MIPS32) big-endian(?), eCos RTOS.
I want to find how bootloader interacts with permanent non-vol memory: what addresses it requests there, all details about boot process and also memory layout addresses.
The initial data (from boot log):

File Length: 1636899 bytes

Load Address: 80004000

Found image 1 at offset 20000

Detected LZMA compressed image... decompressing... 

Target Address: 0x80004000

decompressSpace is 0x4000000

Decompressed length: 7823220

I tried disassembly in the cloud. I have almost no experience with IDA Pro.

Can someone point me in the right direction?